This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our lab is studying the non-ribosomal peptide synthetases, a family of bacterial proteins that synthesize antibiotics and peptide siderophores. These proteins operate in a modular fashion with multiple catalytic domains joined in a single protein. This requires a hand-off of the covalently bound nascent peptide from one domain to the next in the protein assembly line. We have crystallized two important complexes, one of an engineered two-domain, chimeric construct that will allow the characterization of the domain interface. We have also crystallized a complex of these two proteins (not engineered to be a chimeric protein) that appear by gels to have both proteins in the crystal. These crystals currently diffract to only 5A and require synchrotron radiation to find optimum conditions. (We have identified other crystals, including PvdQ (an acylase from Pseudomonas) and Succinate Semialdehyde Dehydrogenase, as well as the chimeric complex such that we will not spend the full time screening.)